7.36CrNiMo4 AISI 4340 Forged steel Application
AISI 4340 steel is used in most industry sectors for applications requiring higher tensile/yield strength than 4140 steel can provide.
Some typical applications such as:

Aircraft Landing Gear
Automotive,
Oil and Gas Drilling,
Forging,
Warm and Cold Forming,
Machine Building,
Transfer Systems, like power transmission gears and shafts.
General engineering industries and structural use applications, such as: heavy duty shafts, gears, axles, spindles, couplings, pins, chucks, molds etc.

8.Quality control:
1. Melting Process: EAF/BOF+LF+VD resulting in ingots
2. Both ends cut by saw
3. Ratio of forging:minimum 3:1
4. Grain size of final product: according to ASTM E112 more than 5,preferred more than 8
5. Ultrasonic test: As per SEP1921 Class C/c or D/d

9.Heat treatment of 36CrNiMo4 AISI 4340Steel

HEAT TREATMENT
Heat treatment after forging is carried out to render the steel suitable for machining, and to meet the mechanical property limits specified for the steel's particular applications. There are several ways to heat treat a given steel part and it is only through practice that the optimum temperature and conditions may be defined. The following information should be taken as a guide only.

ANNEALING
To obtain a pearlitic structure on certain parts for machining, 4340 should be annealed at a nominal temperature of 1525 º F (830 º C,) cooling to 1350 º F (730 º C) and furnace cooling to 1130 º F (610 º C) at a rate of 20 º F (11 º C) per hour, then air cooling. This process, known as full annealing, is very time consuming as it involves slow cooling over the entire temperature range from the austenitizing temperature to a temperature well below that at which transformation is complete.

To obtain a spheroidized structure in 4340 grade involves austenitizing at 1380 º F (750 º C,) furnace cooling to 1300 º F (705 º C) then to 1050 º F (565 º C) at a rate of 5 º F (3 º C) per hour. This structure will probably result in better machinability than will the coarse lamellar pearlite structure obtained by the full anneal process.

NORMALIZING
This process is defined as heating a steel to a temperature above the ferrite to austenite transformation temperature, then cooling in air to a temperature well below this transformation temperature. The treatment may be carried out on forged products as a conditioning treatment prior to final heat treatment. Normalizing also serves to refine the structure of forgings that might have cooled non-uniformly from their forging operation. The nominal normalizing temperature for 4340 grade is 1500 º F (815 º C,) but production experience may necessitate a temperature either 50 º F (10 º C) above or below this temperature. . As a rule of thumb, when forgings are normalized before, say, carburizing or hardening and tempering, the upper range of normalizing temperatures is used. When normalizing is the final heat treatment, the lower temperature range is used.

HARDENING
This heat treatment results in the formation of martensite after quenching, resulting in increased hardness and tensile strength. A temperature range of 1500 - 1550 º F (815 - 845 º C) is the normal austenitizing temperature for direct hardening of 4340 grade. Oil quenching is normally used for 4340 as the alloy's hardenability is suited to this quenching method.

TEMPERING
Tempering is carried out to relieve stresses from the hardening process, but primarily to obtain mechanical properties required for the final application. The actual tempering temperature will be chosen to meet the required properties, and in many cases will be a matter of trial and error.

10.MOQ: one piece per size/grade

11.Payment term: FOB CIF CFR EXW and so on

12.Delivery time : 7 to 30 days after deposit received.